1. Field of the Invention
This invention relates to a method of manufacturing a multi-layer, a non-single-crystalline semiconductor on a substrate, and more particularly to a non-single-crystalline semiconductor manufacturing method which is of particular utility when employed in the fabrication of a semiconductor photoelectric conversion device which may be used as a solar battery.
2. Description of the Prior Art
A semiconductor photoelectric conversion device using a multi-layer, non-single-crystalline semiconductor composed of amorphous or semi-amorphous semiconductor has now been taken notice of because the each non-single-crystalline semiconductor layer may be formed thin, that is, the semiconductor material needed is small in amount and because the photoelectric conversion efficiency can be enhanced, as compared with a semiconductor photoelectric conversion device emplying a multi-layer, single crystal semiconductor.
The following method has heretofore been proposed for manufacturing a multi-layer, non-single-crystalline semiconductor layer on a substrate using following apparatus.
The apparatus for manufacturing a multi-layer, non-single-crystalline semiconductor comprises a single reaction chamber, a plurality of gas sources connected sequentially to the reaction chamber for introducing sequentially into the reaction chamber a plurality of mixture gases each containing at least a semiconductor material gas and a carrier gas, a gas ionizing means as associated with the reaction chamber for ionizing sequentially the plurality of mixture gases introduced sequentially into the reaction chamber to produce sequentially a plurality of mixture gas plasmas, a gas exhaust means connected to the reaction chamber for flowing sequentially the plurality of the mixture gas plasmas through the reaction chamber to effect sequential deposition of a plurality of semiconductor materials onto a substrate and maintaining the pressure in the reaction chamber below one atmosphere, means for maintaining the temperature of the substrate in the reaction chamber at a temperature lower than that at which single-crystallization of the deposited semiconductor materials can occur, whereby the substrate is positioned in the reaction chamber to effect the sequential deposition thereon of the plurality of semiconductor materials to fabricate the multi-layer, non-single-crystalline semiconductor.
Heretofore, the multi-layer, non-single-crystalline semiconductor has been fabricated on the substrate in the following manner using the above-described apparatus.
The substrate is disposed in the reaction chamber, and a first one of the mixture gases is introduced into the reaction chamber from a first one of the gas sources while exhausting the gas through the exhaust means. The mixture gas is ionized by the gas ionizing means into the mixture gas plasma, thereby to deposit a first one of the semiconductor materials on the substrate. In this case, the atmospheric pressure in the reaction chamber is held below one atmosphere and the substrate is maintained at a temperature lower than that at which the semiconductor material deposited on the substrate if formed as a single-crystal semiconductor layer, thereby to obtain a first one of the desired non-single-crystalline semiconductor layers on the substrate.
Next, the supply of the first mixture gas into the chamber is stopped and the gas in the chamber is exhausted by the exhaust means.
Next, a second one of the mixture gases is introduced into the chamber while at the same time exhausting gas by the exhaust means as described above. The mixture gas introduced into the chamber is ionized by the gas ionizing means to generate plasma, thereby depositing a second one of the semiconductor materials on the first non-single-crystalline semiconductor layer. In this case, the atmospheric pressure in the reaction chamber and the substrate temperature are held at the same values as mentioned above. In this way, a second one of the desired non-single-crystalline semiconductor layers is formed on the first non-single-crystalline semiconductor layer.
Thereafter, new non-single-crystalline semiconductor layers are each formed by the same method on a non-single-crystalline semiconductor layer formed immediately prior to it, by which a multi-layer, non-single-crystalline semiconductor is fabricated on the substrate.
As described above, the conventional method employs a single reaction chamber. Accordingly, the prior art method has the defect that a plurality of mixture gases must be selectively introduced into the reaction chamber in a sequential order to fabricate the multi-layer, non-single-crystalline semiconductor on the substrate. Therefore, substrates, each having formed thereon the multilayer, non-single-crystalline semiconductor on the substrate can not be mass-produced in a short time.
Further, since a portion of the gas material for the fabrication of each non-single-crystalline semiconductor layer still remains unremoved in the reaction chamber when starting the fabrication of the next non-single-crystalline semiconductor layer, it is impossible to fabricate the latter non-single-crystalline semiconductor layer of desired characteristics.